docs: def exclude_units(self, unit_ids):
          '''This function deletes roots from the curation tree according to the given unit_ids
  
          Parameters
          ----------
          unit_ids: list
              The unit ids to be excluded
          '''
          root_ids = []
          for i in range(len(self._roots)):
              root_id = self._roots[i].unit_id
              root_ids.append(root_id)
  
          if(set(unit_ids).issubset(set(root_ids)) and len(unit_ids) > 0):
              indices_to_be_deleted = []
              for unit_id in unit_ids:
                  root_index = root_ids.index(unit_id)
                  indices_to_be_deleted.append(root_index)
                  if unit_id in self._unit_features:
                      del self._unit_features[unit_id]
              self._roots = [self._roots[i] for i,_ in enumerate(root_ids) if i not in indices_to_be_deleted]
          else:
              raise ValueError(str(unit_ids) + " has one or more invalid unit ids")